The present invention relates to a transmission device for signals via cables, and more particularly to a single-cable transmission device for signals and a power supply of a surveillance system.
In current surveillance systems, taking a unidirectional surveillance system for an example, base band signals such as video signals, audio signals, control signals, etc. and a power supply between cameras at remote side and monitors at local side are typically transmitted by use of many cables (for example, coaxial cables), respectively. However, such a transmission manner has a number of defects: (1) requiring plural cables, making it difficult to install the system and thus increasing system cost; (2) requiring additional repeaters for longer-distance transmission due to gradual decrease in signal intensity under base band transmission with longer-distance transmission; (3) compounding the problems resulting from the above defects (1) and (2) when the system is to be expanded to a bi-directional one; and (4) generally not easy to directly find whether the power supply or the load (for example, the camera) is out of order when the remote side: which receives the power supply from the local side fails, even though professionals have to take advantage of proper instruments or equipment for assistance to find the cause of the failure so as to eliminate it, not to mention common consumers by DIY (Do-It-Yourself).
In view thereof, the present invention provides an improved single-cable transmission device for signals and a power supply of a surveillance system, which can solve the problems encountered by the above prior art surveillance system techniques.
One object of the present invention is to provide a transmission device, which only requires a single cable to transmit various signals and a power supply, thereby making the system installation convenient, decreasing system cost, and facilitating common consumers to use by DIY.
Another object of the present invention is to provide a transmission device, which transmits signals in a carrier manner, allowing longer-distance transmission.
Still another object of the present invention is to provide a transmission device, which transmits signals in a frequency division manner, allowing bi-directional transmission, and thus facilitating operation drills and improving friendliness with operators.
Yet another object of the present invention is to provide a transmission device, which is equipped with a power-supply-voltage/output-load status display, thereby facilitating a user to directly find the cause of a failure so as to eliminate the failure promptly, and thus saving repair time and enabling common consumers to use by DIY.
According to one embodiment of the present invention, the innovative single-cable transmission device for signals and a power supply of a surveillance system comprises a remote device, said remote device having a first modulator for transforming a first set of base band signals inputted externally into a first modulated carrier signal, and having a first filter module for receiving said first modulated carrier signal and a power supply inputted from said single cable, and for separating said first modulated carrier signal from said power supply through different frequency bands, and then outputting said separated first modulated carrier signal and power supply, respectively, wherein said outputted first modulated carrier signal is applied to said single cable.
According to another embodiment of the present invention, the innovative single-cable transmission device for signals and a power supply of a surveillance system comprises a local device, said local device having a second filter module for receiving said first modulated carrier signal inputted from said single cable and receiving a power supply inputted externally, and for separating said first modulated carrier signal from said power supply through different frequency bands, and then outputting said separated first modulated carrier signal and power supply, respectively, wherein said outputted power supply is applied to said single cable, and having a first demodulator of transforming said first modulated carrier signal outputted from said second filter module into said first set of base band signals.
According to a further embodiment of the present invention, the first filter module of the remote device of the innovative single-cable transmission device for signals and a power supply of a surveillance system further receives a second modulated carrier signal inputted from said single cable, and separates said second modulated carrier signal from said first modulated carrier signal and said power supply through different frequency bands, and then outputs said separated second modulated carrier signal; and said remote device further comprises a second demodulator for transforming said second modulated carrier signal outputted from said first filter module into a second set of base band signals.
According to another embodiment of the present invention, the local device of the innovative single-cable transmission device for signals and a power supply of a surveillance system comprises a second modulator for transforming a second set of base band signals inputted externally into a second modulated carrier signal; a second filter module for receiving said first modulated carrier signal inputted from said single cable, said second modulated carrier signal from said second modulator, and a power supply inputted externally, and for separating said first modulated carrier signal, said second modulated carrier signal, and said power supply through different frequency bands, and then outputted said separated first modulated carrier signal, second modulated carrier and power supply, respectively, wherein said outputted second modulated carrier signal and power supply are applied to said single cable; and a first demodulator for receiving said first modulated carrier signal outputted from said second filter module and transforming said first modulated carrier signals into said first set of base band signals.
According to another embodiment of the present invention, the remote device of the innovative single-cable transmission device for signals and a power supply of a surveillance system comprises a power-supply-voltage/output-load status display connected between the power supply outputted from said first filter module and external devices for detecting the operation status of the power supply voltage and the external device loads.
According to another embodiment of the present invention, the innovative single-cable transmission device for signals and a power supply of a surveillance system receives a power supply at said remote device rather than at said local device as mentioned above.